Expanded metals are materials which have openings in their surface and are produced from a flat material, especially metal plates or metal strips, by making offset cuts without loss of material and concurrently undergoing stretch or expansion forming.
In this connection, the successive cycles (for a vertical alignment of the machine) are as follows:
the flat starting material is guided between knives;
the starting material is cut by the moving knife while being subjected to stretch forming;
the knife is again withdrawn vertically and then adjusted laterally by a half mesh-length;
the knife is again adjusted vertically to cut into the starting material, thereby making first meshes, and the knife is again withdrawn vertically and adjusted laterally into the starting position; and
whereupon, the starting material can again be guided back.
The expanded metal can subsequently be processed further, e.g. rolled flat.
The moving knife is attached to a tool holder, which is laterally adjusted in a synchronized manner with the traveling motion by means of a transverse adjusting device. A cam again adjusts the tool holder in the vertical direction. In this connection, the cam is guided in a sliding guide or roller guide in a conventional manner. Although a sliding guide is first of all easier to construct, it requires good lubrication and does not permit any prestress. In a roller guide, prestress can be provided to eliminate the play that would otherwise arise. However, given that the rollers are only rotated around a small portion of their circumference because of the small stroke (e.g. 3 mm) and the back and forth motion of the cam, they quickly become out-of-round and lock.
U.S. Pat. No. 3,308,597 discloses an expanded metal machine, and a method, in which the respectively movable and adjustable knife is arranged above and the stationary knife is arranged below. The flat sheet-metal material is unrolled from a feed roller, guided between the knives, guided downwards from there over another roller, and stretched and then rolled up on another roller.